Preparation method of high-moisture-resistance titanium dioxide homogeneous out-phase junction room-temperature hydrogen sensor

Abstract

The invention belongs to the technical field of hydrogen sensor preparation, and provides a preparation method of a high-moisture-resistance titanium dioxide homogeneous out-phase junction room-temperature hydrogen sensor, which comprises the following steps: S1, firstly, cleaning an FTO (Fluorine-doped Tin Oxide) substrate; s2, preparing a precursor reaction solution, and growing a titanium dioxide homogeneous out-phase junction film on the FTO substrate through a hydrothermal method; s3, carrying out annealing treatment on the titanium dioxide homogeneous out-phase junction thin film; s4, preparing an impregnation reaction precursor solution, and modifying Pt nanoparticles on the titanium dioxide homogeneous out-phase junction film through an impregnation method; according to the invention, the surface of the titanium dioxide homogeneous out-phase junction film is modified with Pt nanoparticles and coated with the ZSM-5 molecular sieve, so that the moisture resistance of the sensor and the hydrogen response performance at room temperature are improved, and the sensor can stably work in a humid environment; the preparation method disclosed by the invention is simple and controllable, is suitable for large-scale production, and has a relatively high practical application value.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen sensor preparation, in particular to a method for preparing a high moisture-resistant titanium dioxide homogeneous heterogeneous junction room temperature hydrogen sensor. Background Art

[0002] Resistive metal oxide semiconductor (MOS) gas sensors have gradually achieved micro-integration and intelligence due to their unique advantages such as simple manufacturing, excellent performance, and low cost, and their manufacturing processes are becoming more mature, which has promoted their rapid development in the actual application market. With the improvement of market customer application needs and the expansion of application fields, including the Internet of Things (IoT), healthcare, environmental monitoring, and food quality assessment, feedback data statistics show that the change in relative humidity in the detection environment, as a ubiquitous interference factor, significantly affects the gas-sensing performance of resistive MOS gas sensors.

[0003] The sensing mechanism of resistive MOS gas sensors is inseparable from O 2- , O - and O2 - Adsorption on the surface of the gas-sensitive material. During the sensor detection process, the target gas reacts with these oxygen species to release or further capture electrons, causing changes in the device resistance value. TiO2 is a MOS gas-sensitive material with hydrophilic properties. Water molecules in the environment are easily adsorbed on the active sites on the sensing membrane, and electrons are extracted from the reducing water. As the humidity increases, physical adsorption of water gradually begins and forms a whole water layer. The active sites on the surface of the sensor gas-sensitive layer are occupied and the gas diffusion channel is blocked, which greatly weakens the gas-sensitive performance. At the same time, water molecules are ionized into H3O in the electrostatic field. + , and according to the Grotthuss mechanism (H2O+H3O + →H3O + +H2O) transfer, the proton hopping significantly improves the conductivity of the sensing membrane, thereby significantly reducing the resistance of the sensor.

[0004] In order to solve the influence of relative humidity on sensor devices, many surface engineering technologies are applied to improve the moisture resistance of gas-sensitive materials, including but not limited to surface engineering, physical isolation, sensitive material modification, algorithm compensation and new material development. It is worth noting that directly introducing absorbents to capture and detect environmental water molecules is a simple strategy. For example, molecular sieve MCM-48 is used to improve the moisture resistance of Au-SnO2 methanol sensor (doi:10.1016 / j.jallcom.2022.165788); or introducing SBA-15 molecular sieve layer on Pt-In2O3 sensing membrane (doi:10.1038 / s41427-018-0029-2), siloxane bonds are hydrolyzed under high humidity conditions, which can be used as an effective desiccant. Using molecular sieve materials to capture water molecules as a barrier layer to block water vapor and pollution can effectively protect the gas-sensitive center.

[0005] The latest research has found that the interior of the molecular sieve has a large number of evenly distributed three-dimensional spatial pore structures, which is conducive to the selective distinction of molecules of different diameters. Molecules of appropriate sizes pass smoothly, while large molecules are excluded. At the same time, the molecular sieve has abundant polar groups (-OH, -NH2, C=O), or polarizable groups C=C, etc., which make the interior of the molecular sieve crystal cavity have a strong Coulomb field and polarity, so some molecules that are easily polarized or have strong polarity will be selectively adsorbed by the molecular sieve.

[0006] This scheme uses hydrothermal and impregnation methods to grow Nb-doped anatase@rutile TiO2 heterojunctions, deposits metal Pt particles on the surface, and evaporates Al interdigitated electrodes to obtain Pt-modified Nb-doped TiO2 heterojunction room temperature hydrogen sensor. Non-polar molecules), select ionic ZSM-5 molecular sieves with low silicon-aluminum ratio dispersed in propylene glycol, loaded on the surface of the sensor to form a water molecule isolation layer, obtain a high content of hydrophilic Si-OH on the surface to capture water molecules, and achieve the purpose of improving the moisture resistance of the device. Provide a new solution to the humidity interference problem faced by the practical application of room temperature high-performance H2 sensor devices.

[0007] To this end, those skilled in the art have proposed a method for preparing a room temperature hydrogen sensor with high moisture resistance of titanium dioxide homogeneous heterojunction to solve the problems raised by the background technology. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a method for preparing a room temperature hydrogen sensor with a titanium dioxide heterogeneous junction and high moisture resistance, so as to solve the problems existing in the prior art.

[0009] A method for preparing a room temperature hydrogen sensor with a titanium dioxide heterogeneous junction having high moisture resistance comprises the following steps:

[0010] S1, ultrasonically clean the FTO substrate with ethanol, glass cleaning agent, deionized water, and acetone in sequence, and dry it in a drying oven;

[0011] S2. Prepare a hydrothermal reaction precursor solution; prepare a precursor reaction solution 1 composed of water, anhydrous ethanol (analytical grade ≥99.7%), hydrochloric acid (analytical grade 36%-38%), and tetrabutyl titanate (≥99.0%) according to the following volume percentages; the components of the precursor reaction solution 1 are as follows:

[0012]

[0013] S3, pouring a mixture of deionized water, ethanol, hydrochloric acid and butyl titanate into a polytetrafluoroethylene-lined hydrothermal reactor;

[0014] S4, place two cleaned FTO sheets with the conductive surface facing downward in a "V" shape against the inner lining wall of the reactor containing the reaction solution, so that the FTO is immersed in the precursor mixed reaction solution;

[0015] S5. Tighten the reactor and place it in a constant temperature oven for hydrothermal treatment at 150°C (120-180°C) for 8h (4-18h);

[0016] S6. After the reaction is completed, the reactor cooled to room temperature is taken out, the FTO substrate is taken out, and it is washed and soaked with ultrapure water and naturally air-dried;

[0017] S7, annealing the above-mentioned naturally air-dried film sample at 400°C (300-500°C) for 20min (10-60min) in air atmosphere, and the sample is named RT iO2;

[0018] S8, prepare an immersion reaction precursor solution; prepare a precursor reaction solution 2 composed of water, boric acid solution (4% w / v), ammonium hexafluorotitanate (chemically pure 98%), ethanol niobium solution (analytical pure 99.9%), and hydrochloric acid (analytical pure 36%-38%) according to the following volume percentages; the ingredients of the precursor reaction solution 2 are as follows:

[0019]

[0020] S9, pouring the mixed reaction solution of boric acid, deionized water, ammonium hexafluorotitanate and niobium ethanol dissolved in hydrochloric acid into a beaker;

[0021] S10, placing the R-TiO2 sample film prepared in step 7 with its surface tilted downward against the inner lining wall of the beaker containing the reaction solution, and immersing the film sample in the reaction solution 2;

[0022] S11, place the beaker in a constant temperature oven and perform hydrothermal treatment at 80°C (60-90°C) for 8h (4-12h);

[0023] S12. After the reaction is completed, take out the beaker, take out the film, wash and soak it with ultrapure water and let it air dry naturally;

[0024] S13, annealing the thin film sample that has been naturally air-dried in step S12 at 500° C. (300-500° C.) for 120 min (60-180 min) in air atmosphere, and the sample is named NT5 (Nb:Ti atomic ratio is 0.5%);

[0025] S14, preparing a photodeposition reaction precursor solution; preparing a precursor reaction solution 3 composed of water, methanol (analytical grade ≥ 99.7%), and chloroplatinic acid aqueous solution (0.01 g / ml) according to the following volume percentages; the components of the precursor reaction solution 3 are as follows:

[0026] Deionized water: 128 ml (31.4%) Range (112-144 ml)

[0027] Methanol: 32 ml (52.4%) Range (28-36 ml)

[0028] Chloroplatinic acid aqueous solution: 600 μl (0.7%) Range (200-800 μl);

[0029] S15, pouring the mixed reaction solution of methanol, deionized water and chloroplatinic acid into a three-necked flat-bottom beaker;

[0030] S16, vertically placing the thin film sample prepared in step S13 in the precursor solution 3, and purging the precursor solution 3 with nitrogen for about 5 minutes to discharge the air and dissolved oxygen in the three-necked beaker;

[0031] S17, using a 300 W Xe arc lamp as a power source, irradiating the NT5 thin film sample in the precursor solution 3 for 30 min;

[0032] S18. After the photodeposition of Pt particles is completed, the film sample is rinsed with deionized water, soaked for 3 hours, and then naturally air-dried;

[0033] S19, annealing the thin film sample that has been naturally air-dried in step S18 at 400° C. (300-500° C.) for 20 min (5-60 min) in an argon atmosphere, and the sample is named PNT;

[0034] S20, prepare interdigital electrodes; use high temperature glue to align the small interdigital electrode mask with the sample and fix it on the substrate, the substrate is inverted above the evaporation table of the evaporation coating machine (80-120mm), weigh an appropriate amount of Al metal particles with a purity of 99% and put them into the tungsten boat, set the film thickness monitor value to 500nm, evacuate the evaporation chamber until the pressure reaches below 10-3Pa, and start evaporation; when the thickness of the evaporated Al interdigital electrode reaches 500nm, the evaporation electrode is completed, and a Pt-modified Nb-doped TiO2 isojunction gas sensor is obtained;

[0035] S21, preparing a molecular sieve dispersion solution; preparing a ZSM-5 molecular sieve dispersion 1 composed of glycerol (analytical purity ≥99.7%) and ZSM-5 molecular sieve (crystallinity ≥95%) in the following volume percentages; the composition of the ZSM-5 molecular sieve dispersion 1 is as follows:

[0036] Glycerol: 200 μl (0.01%) Range (0.166-0.498 g)

[0037] ZSM-5 molecular sieve: 0.009g (0.4%) Range (0.001-0.015g)

[0038] S22, using a pipette to take 2 μl of the ZSM-5 molecular sieve dispersion and evenly coat the surface of the film sample prepared in step 20;

[0039] S23. The coated sample is placed in a constant temperature oven and dried at 100°C (90-120°C) for 12h (10-14h); after drying, the sensor is named ZPNTX (X is the amount of different molecular sieves in dispersion 1, which are 0.001, 0.003, 0.005, 0.007, 0.009, 0.011, and 0.015g respectively).

[0040] The invention relates to a highly moisture-resistant titanium dioxide heterojunction room-temperature hydrogen sensor, the working principle of which is based on the selective adsorption and desorption of hydrogen by the titanium dioxide heterojunction at room temperature; by preparing a titanium dioxide heterojunction film with a specific structure, combined with the modification of Pt nanoparticles and the coating of ZSM-5 molecular sieves, the moisture resistance of the sensor and the hydrogen response performance at room temperature are improved.

[0041] Specifically, the present invention adopts a hydrothermal method and an impregnation method to prepare a titanium dioxide isomorphous heterogeneous junction film composed of anatase and rutile phases, and deposits Pt nanoparticles on the surface of the film by a photodeposition method; the Pt nanoparticles act as a catalyst, which can reduce the adsorption activation energy of hydrogen on the titanium dioxide surface and improve the response speed of the sensor; the present invention also adopts a ZSM-5 molecular sieve to coat the surface of the sensor, and the moisture resistance of the sensor is further improved through the adsorption effect of the molecular sieve.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The present invention improves the moisture resistance and hydrogen response performance of the sensor at room temperature by modifying Pt nanoparticles and coating ZSM-5 molecular sieve on the surface of the titanium dioxide isojunction film, so that the sensor can work stably in a humid environment;

[0044] 2. The preparation method of the present invention is simple, controllable, suitable for large-scale production, and has high practical application value;

[0045] 3. The sensor of the present invention has high sensitivity and fast response speed, and can meet the needs of the field of hydrogen safety monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of the sensor device structure and moisture resistance mechanism of the present invention;

[0047] Figure 2 The microscopic surface morphology and macroscopic device diagram of the unloaded molecular sieve and the loaded molecular sieve with different contents of ZSM-5 of the present invention: (a) PNT; (b) ZPNT1; (c) ZPNT3; (d) ZPNT5; (e) ZPNT7; (f) ZPNT9; (g) ZPNT11; (h) ZPNT15;

[0048] Figure 3 The gas-sensitive response curve of the sensor PNT of the present invention at different humidity in 1000ppm H2 at room temperature;

[0049] Figure 4 The gas-sensitive response curve of the sensor ZPNT1 of the present invention at different humidity in 1000ppm H2 at room temperature;

[0050] Figure 5 The gas-sensitive response curve of the sensor ZPNT3 of the present invention at different humidity in 1000ppm H2 at room temperature;

[0051] Figure 6 The gas-sensitive response curve of the sensor ZPNT5 of the present invention at different humidity in 1000ppm H2 at room temperature;

[0052] Figure 7 The gas-sensitive response curve of the sensor ZPNT7 of the present invention at different humidity in 1000ppm H2 at room temperature;

[0053] Figure 8 The gas-sensitive response curve of the sensor ZPNT9 of the present invention at different humidity in 1000ppm H2 at room temperature;

[0054] Fig. 9 The gas-sensitive response curve of the sensor ZPNT11 of the present invention at different humidity in 1000ppm H2 at room temperature;

[0055] Fig.10 The gas-sensitive response curve of the sensor ZPNT15 of the present invention at different humidity in 1000ppm H2 at room temperature;

[0056] Fig.11 It is a comparison diagram of the responses of sensors PNT, ZPNT1, ZPNT3, ZPNT5, ZPNT7, ZPNT9, ZPNT11 and ZPNT15 with different molecular sieve loading amounts before and after loading molecular sieve at room temperature in the relative humidity range of 20%-80%.

[0057] Fig.12 The three groups of response drift values ​​(I f-20％ ,I f-40％ and I f-60％ )Comparison chart of calculation results. DETAILED DESCRIPTION

[0058] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0059] Combination Figure 1 and Figure 2 As shown:

[0060] Figure 1 The sensor consists of a gas-sensitive layer formed by growing a Pt-modified Nb-doped TiO2 heterojunction thin film on a FTO substrate, an Al interdigitated electrode, and a surface anti-humidity layer. The anti-humidity layer is composed of ZSM-5 molecular sieves uniformly dispersed in propylene glycol. The molecular sieve has a highly polarized internal structure with regular pores and a large number of uniformly distributed channels. Compared with the larger molecular diameter Polar water molecules, H2 molecules have a smaller diameter And it is non-polar. Therefore, when the two pass through the anti-humidity layer together, the H2 molecule preferentially enters the pores of the molecular sieve under the strong attraction, reaches the gas-sensitive layer and reacts with the surface active sites; the water molecules are captured by the molecular sieve containing a large number of Si-OH hydrophilic groups on the surface. At the same time, propylene glycol has a strong adsorption and moisture retention ability for water molecules, isolating the water molecules from the outside and making it difficult for them to approach the core gas-sensitive material, thus obtaining a room temperature high-response hydrogen sensor device with excellent moisture resistance;

[0061] Figure 2In the comparison of the PNT sample without molecular sieve loading, after loading the ZSM-5 molecular sieve, it was observed that the ZSM-5 molecular sieve was successfully loaded on the PNT sensor. There are only a small amount of ZSM-5 molecular sieve on the surface of ZPNT1 and ZPNT3, and there is no connection to form a film on the surface. There is still a large amount of PNT film exposed to the air. It is difficult to see the ZSM-5 molecular sieve layer in the corresponding sensor physical picture. The surface of ZPNT5 and ZPNT7 is gradually covered by ZSM-5 molecular sieve, but the overall distribution is uneven, and the surface ZSM-5 molecular sieve barrier layer is uneven; until the loading content is 0.009, the surface of the ZPNT9 sensor is highly consistent and evenly distributed, and is covered by the ZSM-5 molecular sieve barrier layer with good overall film-forming properties. This can also be observed from the physical picture of the sensor. By further increasing the ZSM-5 molecular sieve content, the surface of ZPNT11 and ZPNT15 is densely stacked with the ZSM-5 molecular sieve barrier layer. By comparing the actual pictures of all sensor devices, it can be obviously found that the thickness of the ZSM-5 molecular sieve barrier layer in the PNT11 and ZPNT15 samples increases, making their film-forming properties poor, the adhesion is poor, and it is easy to fall off.

[0062] Changes in relative humidity in the test environment can cause changes in the initial resistance and response value of the sensor. The baseline resistance drift (R ad ) and response drift (I f ) is used to evaluate the effect of humidity on sensor resistance and response and is defined as formulas (1) and (2):

[0063] R ad =|R a-L％RH -R a-H％RH | / R a-L％RH (1)

[0064] I f =|S L％RH -S H％RH | / S L％RH (2)

[0065] Among them, R a-L％RH and R a-H％RH Respectively represent the baseline resistance of the sensor in low humidity and high humidity test environments with a stable trend. S L％RH and S H％RH They represent the response values ​​of the sensor after the target gas is introduced into the low humidity and high humidity test environments, respectively. a-L％RH and S L％RH Based on the baseline resistance and response at 20% relative humidity, the baseline resistance drift and response drift at 40%, 60%, and 80% relative to 20% are calculated and named R ad-20％ , R ad-40％ , R ad-60％ and I f-20％ ,I f-40％ ,If-60％ .

[0066] Combination Figures 3 to 10 As shown:

[0067] Figures 3 to 10 Shown are gas response curves of a PNT sensor without molecular sieve loading and a ZPNTX (X=1-15) sensor loaded with different molecular sieve amounts at room temperature and 1000ppm H2 from relative humidity 20%, 40%, 60% to 80% at four different ambient humidity conditions;

[0068] The PNT sensor has a large baseline resistance. The baseline resistance gradually decreases with the increase of humidity at a relative humidity of 20% to 80%, and is 6GΩ, 2.1GΩ, 860MΩ, and 435MΩ respectively. The three groups of baseline drift R ad-20％ , R ad-40％ and R ad-60％ The values ​​of ZPNT1 and ZPNT3 are 65%, 85.7% and 92.8% respectively, which are greatly affected by humidity. After loading a trace amount of molecular sieve, the baseline resistance of ZPNT1 and ZPNT3 sensors changes with humidity in the same trend as that of PNT sensors, but the baseline drift decreases. By continuing to increase the loading amount of molecular sieve (0.005-0.007), the baseline drift problem of ZPNT5 sensor is reduced compared with that of ZPNT1 and ZPNT3 sensors; the baseline drift of ZPNT7 sensor under high humidity changes is R ad-60％ Only 7.1%, indicating that the influence of humidity on the baseline resistance of the sensor is successfully compensated by the molecular sieve loading. When the molecular sieve loading is 0.009, the surface molecular sieve layer is densely packed to form a thicker molecular sieve layer, which makes the baseline resistance gradually increase with the increase of relative humidity, and the response is less affected by humidity. Further increasing the surface molecular sieve loading to 0.015, the excessive surface molecular sieve loading causes the baseline resistance of the ZPNT11 and ZPNT15 sensors to decrease with the increase of humidity, the baseline drift increases, and the response is significantly disturbed by humidity changes.

[0069] Combination Fig.11 As shown in the figure: The maximum error of the PNT sensor response without molecular sieve loading is 1.75, and the average response values ​​at 20%, 40%, 60% and 80% relative humidity are 10.5, 6.1, 3.8 and 2.4 respectively. The response value decreases significantly with the increase of relative humidity. The sensor response increases after loading molecular sieve. When the molecular sieve content is 0.009, the barrier layer on the surface of the ZPNT9 sensor is evenly covered to form a good cross-linked structure. 20％RH , S 40％RH , S 60％RH and S 80％RHThe response values ​​are 25.85, 22.6, 26.9 and 26 respectively. Compared with other samples, the response increases and is less affected by humidity. It is worth noting that it can still maintain a high response in a high humidity environment, and even higher than the response in a low humidity environment. When the surface molecular sieve is excessively accumulated, the responses of ZPNT11 and ZPNT15 sensors in a 20% humidity environment are 20.6 and 16.36 respectively. Compared with the ZPNT9 sensor, not only the response value is reduced, but also the influence of humidity is increased. The responses are 5.65 and 4.14 respectively at 80% humidity, indicating that excessive molecular sieve loading is not conducive to gas diffusion and thus weakens the device's response to hydrogen.

[0070] Combination Fig.12 As shown:

[0071] Response Drift I f It is considered to be an important indicator for evaluating the moisture resistance of sensors. f The smaller it is, the better the sensor's moisture resistance is. Fig.12 It was found that the response drift of the PNT sensor without molecular sieve loading increased with the increase of humidity, which is consistent with the general trend that the response of most MOS gas sensors is disturbed by humidity. f The phenomenon of decreasing first and then increasing with the molecular sieve loading amount is presented, that is, the moisture resistance increases first and then decreases. Among them, the ZPNT9 sensor has the smallest response drift, and the higher the relative humidity, the better the moisture resistance, and it also shows the best moisture resistance among all sensors. This means that choosing the right amount of molecular sieve to load will take into account both the good effect of isolating water molecules and high air permeability, so that the ZPNT9 sensor loaded with molecular sieve not only has an increased response compared to the PNT sensor without molecular sieve loading, but also shows excellent moisture resistance.

[0072] From the above, we can get Table 1 and Table 2:

[0073]

[0074] Table 1 Three groups of baseline drift values ​​of PNT sensor without molecular sieve loading and ZPNTX sensor with different molecular sieve loading (X=1-15)

[0075] It can be seen from Table 1 that, by comparing the baseline drift sizes of different sensors in Table 1, the baseline drift after loading the molecular sieve is smaller than that of the sensor without the molecular sieve. The baseline resistance value is disturbed by the humidity change and shows an overall trend of first decreasing and then increasing. This shows that selecting an appropriate amount of molecular sieve load can reduce the impact of the humidity change in the test environment on the baseline resistance value of the room temperature MOS sensor.

[0076]

[0077] Table 2 Three groups of response drift values ​​of PNT sensor without molecular sieve loading and ZPNTX sensor with different molecular sieve loading (X=1-15)

[0078] It can be obtained from Table 2 that Table 2 shows the I of the PNT sensor without molecular sieve loading. f-20％ ,I f-40％ and I f-60％ The sensor response is greatly affected by humidity. The response drift of all sensors loaded with molecular sieve is smaller than that of PNT sensors without molecular sieve, and the response drift decreases first and then increases with the increase of molecular sieve amount. f-20％ ,I f-40％ and I f-60％ They are 12.6%, 4.1% and 0.5% respectively, with the smallest response drift, that is, the ZPNT9 sensor has the best moisture resistance.

[0079] The embodiments of the present invention are provided for the purpose of illustration and description. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A highly moisture-resistant titanium dioxide heterojunction room temperature hydrogen sensor, Features: The invention comprises an FTO substrate and a titanium dioxide heterogeneous junction film grown on the FTO substrate. The titanium dioxide heterogeneous junction film consists of anatase phase and rutile phase, and the film surface is modified with Pt nanoparticles and coated with ZSM-5 molecular sieve.

2. A highly moisture resistant titanium dioxide heterojunction room temperature hydrogen sensor as claimed in claim 1, Features: The Pt nanoparticles are deposited on the surface of the titanium dioxide heterogeneous junction film by a photodeposition method.

3. A highly moisture resistant titanium dioxide heterogeneous junction room temperature hydrogen sensor as claimed in claim 1, Features: The ZSM-5 molecular sieve is uniformly covered on the surface of the titanium dioxide isomorphous heterogeneous junction film modified with Pt nanoparticles by coating.

4. A method for preparing a highly moisture-resistant titanium dioxide heterogeneous junction room temperature hydrogen sensor according to any one of claims 1 to 3, Features: The following steps are involved: S1, first clean the FTO substrate; S2, preparing a precursor reaction solution, and growing a titanium dioxide heterogeneous junction thin film on a FTO substrate by a hydrothermal method; S3, then annealing the titanium dioxide heterogeneous junction film; S4, preparing an impregnation reaction precursor solution, and modifying Pt nanoparticles on the titanium dioxide heterogeneous phase junction film by an impregnation method; S5, then annealing the titanium dioxide heterogeneous junction film modified with Pt nanoparticles again; S6. preparing interdigital electrodes; S7, preparing a molecular sieve dispersion solution, and coating the ZSM-5 molecular sieve on the surface of the titanium dioxide heterogeneous junction film modified with Pt nanoparticles; S8. Finally, the film coated with the ZSM-5 molecular sieve is dried.

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